Publications

@article{gilio_pressure-induced_2025,

title = {The pressure-induced stiffening of quartz and its effect on the strain-stress relationship. Implications for elastic geobarometry},

author = {Mattia Gilio and Ross J. Angel and Mattia L. Mazzucchelli and Matteo Alvaro},

url = {https://www.sciencedirect.com/science/article/pii/S0024493725002695},

doi = {10.1016/j.lithos.2025.108210},

issn = {0024-4937},

year  = {2025},

date = {2025-11-01},

urldate = {2025-11-01},

journal = {Lithos},

volume = {514-515},

pages = {108210},

abstract = {Elastic geobarometry allows us to estimate the pressure and temperature conditions of the entrapment of a mineral within a host from the residual pressure of the inclusion. The residual pressure is often calculated as the mean normal stress by applying the elastic tensor (Cij) measured at ambient pressure (1 bar) to the measured inclusion strains. While neglecting the pressure dependence of the Cij is a reasonable assumption for stiffer minerals such as olivine and zircon, this method may induce significant errors in the calculation of inclusion pressures and hence entrapment conditions of softer minerals like quartz trapped in stiff hosts such as garnets. Here we describe a method to calculate stress from the measured strains of quartz inclusions by considering the progressive stiffening of the elastic tensor of quartz with pressure, and discuss its implications for elastic geobarometry. Additionally, we extend this method to the stiffer olivine and zircon to emphasise its broader utility to ultra-high-pressure and temperature rocks and inclusions in diamonds. The changes in inclusion pressures for these latter two minerals are, however, not as significant as those in quartz, and it can be assumed that the elastic tensor remains invariant with pressure for most geological cases. A MATLAB code is provided with a comprehensive guide to calculate the inclusion pressures accounting for the change in the elastic tensor with pressure for quartz, olivine, and zircon. This code will be implemented within future updates of the online platform for elastic geothermobarometry EntraPT (https://www.mineralogylab.com/software/entrapt).},

keywords = {Elastic thermobarometry, Elasticity, QuiG, Raman thermobarometry},

pubstate = {published},

tppubtype = {article}

}

@article{gonzalez_elastic_2025,

title = {Elastic thermobarometry of natural and experimental quartz inclusions in garnet (QuiG) under tension},

author = {Joseph P. Gonzalez and Mattia L. Mazzucchelli and Jay B. Thomas and Ross J. Angel and Robert S. Darling and Khi X. Atchinson and Mattia Gilio and Matteo Alvaro},

url = {https://doi.org/10.1007/s00410-025-02252-2},

doi = {10.1007/s00410-025-02252-2},

issn = {1432-0967},

year  = {2025},

date = {2025-09-01},

urldate = {2025-09-01},

journal = {Contributions to Mineralogy and Petrology},

volume = {180},

number = {10},

pages = {70},

abstract = {Elastic thermobarometry has been rarely applied to quartz inclusions entrapped in garnet (QuiG) in granulite and igneous terranes, in part, because there is uncertainty about the reliability of the thermobarometric results arising from the quartz inclusions being subject to tensile strain and stress when examined at room conditions. Here, we present QuiG results from high-temperature metapelites from the Adirondacks, NY, USA and piston-cylinder experiments that give insight into the deformation behavior of quartz inclusions under tension. Measured remnant pressures (Pinc) of experimental and natural samples calculated using the quartz phonon mode Grüneisen tensor are too tensile with respect to the expected Pinc values based on experimental and petrologic constraints. We show that these discrepancies are not related to non-elastic deformation nor inaccuracies in the quartz equation of state. Evaluation of previous density functional theory (DFT) results shows that the structural response of quartz is non-linear with increasing tensile strain. Therefore, because the available quartz phonon mode Grüneisen tensor was determined with a linear fit optimized for compressive strains, obtained tensile strains using this tensor are too large in magnitude. Pinc values obtained using the hydrostatic calibrations of the 128 and 464 cm−1 peaks have better agreement with the expected values and return entrapment conditions that are consistent with petrologically constrained or known experimental pressures. Pinc values obtained through hydrostatic calibrations must nonetheless be treated with caution because the behavior of Raman phonon modes under tension has not been calibrated experimentally.},

keywords = {Elastic thermobarometry, Elasticity, Garnet, Quartz, QuiG, Raman thermobarometry},

pubstate = {published},

tppubtype = {article}

}